1. Field of Disclosure
The present disclosure of invention relates to a substrate transferring unit, a substrate processing apparatus including the substrate transferring unit and a method of processing a substrate using the substrate processing apparatus. More particularly, the present disclosure of invention relates to a substrate transferring unit configured for protecting a processed surface of a substrate, a substrate processing apparatus including the substrate transferring unit and a method of processing a substrate using the substrate processing apparatus.
2. Description of Related Technology
A roll-to-roll processing means can operate on a thin flexible substrate which is part of a continuum of such flexible substrates and which can continuously be transferred from a supplying roll to a receiving roll. The substrate may include one of a paper, a flexible plastic, a flexible metal foil and a flexible thin glass.
Recently, a flexible display apparatus has been developed. The flexible display apparatus can be made to have a light weight such that it is portable, economical and durable. The use of roll-to-roll processing for manufacturing a display panel of the flexible display kind is contemplated here. By using roll-to-roll processing, the manufacturing of the flexible display panel may be more automatized and may become faster than a manufacturing process where in-process substrates are individually operated on. Thus, a mass productivity of flexible-type display apparatuses may be improved.
Generally, when transferring rolls respectively make contact with an upper surface of a flexible substrate on which a manufacturing process is being carried out and also make contact with a lower surface of the substrate opposite to the upper surface, the being-processed surface of the substrate may be damaged. For example, the processed surface of the substrate may be scratched. More specifically, when the transferring roll makes contact with a processed surface of a substrate of the display panel, a signal wiring on the substrate may become disconnected (e.g., broken into an opened circuit state) so that a productivity and a reliability of the display panel may be deteriorated. In addition, a stress-induced stain may be shown on a latter viewed portion of the substrate so that a display quality of the display panel may be deteriorated.
When a process of attaching a separate protecting sheet and a process of detaching the protecting sheet are added to protect the processed surface of the substrate, a manufacturing cost of the display panel may be disadvantageously increased. In addition, the processed surface may be stained during the processes of attaching and detaching the protecting sheet. For example, when an alignment layer which is relatively sensitive, has a protecting sheet attached and/or detached therefrom, the alignment layer may lose an alignment force by the protecting sheet.
To protect the processed surface of the substrate, a step-type transferring roll may be employed. The step-type transferring roll has a recessed portion corresponding to a central portion so that the central portion of the step-type transferring roll does not make contact with the substrate. Only side portions of the step-type transferring roll make contact with the substrate to transfer the substrate. Thus, a transferring force of the step-type transferring roll is relatively weak. In addition, when a dimension of the step-type transferring roll making contact with the substrate is increased so as to increase contact area, a usage efficiency of the substrate may be decreased.
To protect the processed surface of the substrate, an air levitation transferring roll may be employed. When the air levitation transferring roll is used to transfer the substrate, a noise may be generated and a manufacturing cost of the display panel may be increased. In addition, the air levitation transferring roll requires presence of air so that the air levitation transferring roll may not be used in combination with a vacuum manufacturing process.
It is to be understood that this background of the technology section is intended to provide useful background for understanding the here disclosed technology and as such, the technology background section may include ideas, concepts or recognitions that were not part of what was known or appreciated by those skilled in the pertinent art prior to corresponding invention dates of subject matter disclosed herein.